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It has been a busy day for the Black Cats boss, who has also tied up a big-money agreement for Wolves striker Steven Fletcher.

Fletcher will welcome the news of Johnson's arrival, with the talented 25-year-old set to provide the ammunition he thrives on from the flanks.

Sunderland have pulled off quite a coup in landing a man widely considered to be among the best technical performers in England.

Quality

Manchester City's decision to snap him up in 2010 proved how highly he is thought of, and he formed part of their Premier League title-winning squad last season.

Johnson did, however, struggle to hold down a regular role at City throughout his time at the Etihad Stadium and grew increasingly frustrated at life in the shadows.

In order to bring consistency to his game, and to aid his claims to an international spot, he believes a return to his native North East - where he has previously turned out for Middlesbrough - is the best decision for him at this stage of his career.

On securing Johnson.s signature, O'Neill told Sunderland's official website: "Adding quality players to the squad has been our main aim this summer and Adam certainly fits that bill.

"He has terrific ability, great delivery and I'm sure he is a player who will excite our fans.